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to turn on and off digital outputs I use the code from sbus.c: sbuslock(); setdiopin(pin, val); sbusunlock(); //code is below.... now this is fine and dandy for setting a single pin on or off, but what if I want to set a bank of DIO's (say pin 31 and 33 ) to both on at the same time. when I do the setdiopin(31,val); setdiopin(33,val); they don't happen at the same time but rather on after the other. Now I can see in the code they are bit-mapping, and filtering, but I'm lost in the 1's compliment, and shifting: pinOffSet = pin - 21; sbus_poke16(0x6c, sbus_peek16(0x6c) & ~(1 << pinOffSet)); can someone explain what is happening with the above statement? sbus_poke16 looks to me as if it is writing an 8-bit value to the address 0x6c, and its masking to ~(1<<pinOffSet) but I'm getting lost. TIA, Jleslie /******************************************************************************* * setdiopin: accepts a DIO register and value to place in that DIO pin. * Values can be 0 (low), 1 (high), or 2 (z - high impedance). *******************************************************************************/ void setdiopin(int pin, int val) { int pinOffSet; int dirPinOffSet; // For Register 0x66 only int outPinOffSet; // For Register 0x66 only // First, check for the high impedance case if (val == 2) { if (pin <= 40 && pin >= 37) { dirPinOffSet = pin - 33; sbus_poke16(0x66, sbus_peek16(0x66) & ~(1 << dirPinOffSet)); } else if (pin <= 36 && pin >= 21) { pinOffSet = pin - 21; sbus_poke16(0x6c, sbus_peek16(0x6c) & ~(1 << pinOffSet)); } else if (pin <= 20 && pin >= 5) { pinOffSet = pin - 5; sbus_poke16(0x72, sbus_peek16(0x72) & ~(1 << pinOffSet)); } } /******************************************************************* *0x66: DIO and tagmem control (RW) * bit 15-12: DIO input for pins 40(MSB)-37(LSB) (RO) * bit 11-8: DIO output for pins 40(MSB)-37(LSB) (RW) * bit 7-4: DIO direction for pins 40(MSB)-37(LSB) (1 - output) (RW) ********************************************************************/ else if (pin <= 40 && pin >= 37) { dirPinOffSet = pin - 33; // -37 + 4 = Direction; -37 + 8 = Output outPinOffSet = pin - 29; // set bit [pinOffset] to [val] of register [0x66] if(val) sbus_poke16(0x66, (sbus_peek16(0x66) | (1 << outPinOffSet))); else sbus_poke16(0x66, (sbus_peek16(0x66) & ~(1 << outPinOffSet))); // Make the specified pin into an output in direction bits sbus_poke16(0x66, sbus_peek16(0x66) | (1 << dirPinOffSet)); /// } /********************************************************************* *0x68: DIO input for pins 36(MSB)-21(LSB) (RO) *0x6a: DIO output for pins 36(MSB)-21(LSB) (RW) *0x6c: DIO direction for pins 36(MSB)-21(LSB) (1 - output) (RW) *********************************************************************/ else if (pin <= 36 && pin >= 21) { pinOffSet = pin - 21; // set bit [pinOffset] to [val] of register [0x6a] if(val) sbus_poke16(0x6a, (sbus_peek16(0x6a) | (1 << pinOffSet))); else sbus_poke16(0x6a, (sbus_peek16(0x6a) & ~(1 << pinOffSet))); // Make the specified pin into an output in direction register sbus_poke16(0x6c, sbus_peek16(0x6c) | (1 << pinOffSet)); /// } /********************************************************************* *0x6e: DIO input for pins 20(MSB)-5(LSB) (RO) *0x70: DIO output for pins 20(MSB)-5(LSB) (RW) *0x72: DIO direction for pins 20(MSB)-5(LSB) (1 - output) (RW) *********************************************************************/ else if (pin <= 20 && pin >= 5) { pinOffSet = pin - 5; if(val) sbus_poke16(0x70, (sbus_peek16(0x70) | (1 << pinOffSet))); else sbus_poke16(0x70, (sbus_peek16(0x70) & ~(1 << pinOffSet))); // Make the specified pin into an output in direction register sbus_poke16(0x72, sbus_peek16(0x72) | (1 << pinOffSet)); } } void sbus_poke16(unsigned int adr, unsigned short dat) { unsigned int dummy; if (last_gpio_adr != adr >> 5) { last_gpio_adr = adr >> 5; cvgpioregs[0] = (cvgpioregs[0] & ~(0x3<<15))|((adr>>5)<<15); } adr &= 0x1f; asm volatile ( "mov %0, %1, lsl #18\n" "orr %0, %0, #0x800000\n" "orr %0, %0, %2, lsl #3\n" "3: ldr r1, [%3, #0x64]\n" "cmp r1, #0x0\n" "bne 3b\n" "2: str %0, [%3, #0x50]\n" "1: ldr r1, [%3, #0x64]\n" "cmp r1, #0x0\n" "beq 1b\n" "ldr %0, [%3, #0x58]\n" "ands r1, %0, #0x1\n" "moveq %0, #0x0\n" "beq 3b\n" : "+r"(dummy) : "r"(adr), "r"(dat), "r"(cvspiregs) : "r1","cc" ); } unsigned short sbus_peek16(unsigned int adr) { unsigned short ret; if (last_gpio_adr != adr >> 5) { last_gpio_adr = adr >> 5; cvgpioregs[0] = ((adr>>5)<<15|1<<3|1<<17); } adr &= 0x1f; asm volatile ( "mov %0, %1, lsl #18\n" "2: str %0, [%2, #0x50]\n" "1: ldr r1, [%2, #0x64]\n" "cmp r1, #0x0\n" "beq 1b\n" "ldr %0, [%2, #0x58]\n" "ands r1, %0, #0x10000\n" "bicne %0, %0, #0xff0000\n" "moveq %0, #0x0\n" "beq 2b\n" : "+r"(ret) : "r"(adr), "r"(cvspiregs) : "r1", "cc" ); return ret; } __._,_.___ Posted by: __,_._,___ |